The problem is that the cost of an interceptor is a magnitude higher than a single missile. So it's easier to just build 10 missiles for every interceptor. You can also put multiple warheads on a single missile, or use decoys/countermeasures to defeat an interceptor.
Our current mid-course interceptors only have about a 50% success rate if I remember correctly, and terminal interceptors only cover a small range. There is a reason why we only deploy interceptors to geo-politically important theaters like Israel or Korea:
1. Because we only need to intercept intermediate-range or short range ballistic missiles
2. They are pinpoint areas that yield large amounts of coverage (of human lives) for a single deployment
It wouldn't be possible to blanket the US population centers in interceptor sites. Even if we could, our current radar systems wouldn't detect hypersonic missiles before its too late, meaning we would need a satellite fleet to detect launches from space. MAD is going to be the best option.
Our current mid-course interceptors only have about a 50% success rate if I remember correctly, and terminal interceptors only cover a small range. There is a reason why we only deploy interceptors to geo-politically important theaters like Israel or Korea:
1. Because we only need to intercept intermediate-range or short range ballistic missiles
2. They are pinpoint areas that yield large amounts of coverage (of human lives) for a single deployment
It wouldn't be possible to blanket the US population centers in interceptor sites. Even if we could, our current radar systems wouldn't detect hypersonic missiles before its too late, meaning we would need a satellite fleet to detect launches from space. MAD is going to be the best option.